Terminal of socket connector

ABSTRACT

A socket connector includes a housing positioned on a circuit board and movably supporting a cover. Cells are defined in the housing for retaining dual-beam terminals. The cover carries a central processing unit module having pin legs extending through holes defined in the cover and projecting into the cells of the housing. The cover is movable in a moving direction to bring the pin legs into engagement with the terminals. Each terminal includes a base section retained in each cell and a tail extending and beyond the housing for being soldered to the circuit board. Two beams extend from the base section, substantially opposite to the tail. Each beam forms a spring arm. The spring arms are opposite to and spaced from each other for engaging the corresponding pin leg therebetween. The beams are symmetric with respect to an imaginary plane that is normal to the base section and coincident with the moving direction. Each beam has a major surface angularly offset from the imaginary plane and thus forming a first included angle with the imaginary plane. The major surface also forms a second included angle with the base section. The included angles are smaller than 90 degrees and greater than 0 degree. Preferably, the included angles are 45 degrees. The angularly offset configuration of the beams allows easy adjustment of the space between the spring arms and thus adjustment of the performance parameters of the terminals.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a socket connector comprisingconductive terminals for electrically connecting an electronic device,such as a central processing unit (CPU) module, to a circuit board, andmore particular to the structure of the terminals.

2. The Related Arts

Socket connectors for mounting an electronic device, such as a centralprocessing unit (CPU) module, to a circuit board are well known and arecommonly used in the computer industry. FIG. 1 of the attached drawingsshows an example of the socket connectors that is referred to as ZIF(Zero Insertion Force) socket connector. The socket connector, generallydesignated with reference numeral 10, comprises a housing 12, made of aninsulation material, defining an array of open cells 14 in whichconductive terminals (not shown in FIG. 1) are received and a cover 16movably supported on the housing 12. The cover 16 defines through holes18 corresponding to the cells 14 of the housing 12. The cover 16 carriesa CPU module 20 with pin legs 22 of the CPU module 20 extending throughthe holes 18 of the cover 16 and partially projecting into the cells 14.An actuator 24 drives the cover 16 to move in a predetermined directionA in such a manner to bring the pin legs 24 of the CPU module 20 intocontact with the terminals of the housing 12 thereby forming electricalconnection therebetween. Examples of socket connectors of this type arealso disclosed in U.S. Pat. Nos. 4,498,725, 5,833,483, 6,059,596,6,142,8 10, and 6,159,032.

A number of different terminals for the socket connectors are available.They can be roughly classified as single-beam terminals and dual-beamterminals. Terminals of both types have a base section received andsecurely retained in the cell of the housing and a tail extending fromthe base and beyond a lower face of the housing for being soldered tothe circuit board. A signal-beam terminal has a single beam extendingfrom base section substantially in a direction opposite to the tail andforming a spring arm on a free end of the beam, while a dual-beamterminal has two beams opposite to each other. An example of the dualbeam-terminal is illustrated in U.S. Pat. No. 4,498,725 and shown isFIG. 2 of the attached drawings. The dual-beam terminal, generallydesignated with reference numeral 30 in FIG. 2, comprises a base section32 and a tail 34 extending from the base section 32 in a downwarddirection (as viewed in FIG. 2). Two beams 36 extend from the basesection 32 in an upward direction that is substantially opposite to thedownward direction of the tail 34. The beams 36 are opposite to eachother and spring arms 38 are formed on free ends thereof and extendingin a horizontal direction substantially parallel to the predetermineddirection A and normal to the upward and downward directions. Free ends40 of the spring arms 38 are convergent to each other for reducing thespace therebetween.

Since the beams 36 and the spring arms 38 are made substantiallyopposite to each other, forming a mirror symmetry configuration. The pinleg 22 of the CPU module 20 that engages with the spring arms 38 of theterminal 30 is first inserted into the space between the spring arms 38.When the cover 16 moves in the direction A, the pin leg 22 is driveninto the reduced space between the free ends 40 of the spring arms 38for forming electrical connection therebetween.

The terminal 30 is usually made by stamping a metal plate, followed bymechanically forming the beams 36 and the spring arms 38.Conventionally, a major surface of each beam 36 is made substantiallyparallel to an imaginary plane defined by the direction A and the upwarddirection whereby the pin leg 22 is guided in the direction A. Such aconventional design suffers certain deficiencies. For example, the gapsize between the free ends 40 of the spring arms 38 is difficult toadjust. Spring rate of the spring arms 38 is also difficult to adjustand this in turn makes the normal force acting upon the pin leg 22 bythe spring arms 38 difficult to adjust in order to achieve optimumelectrical and mechanical engagement between the spring arms 38 and thepin leg 22. Such deficiencies are even more severe in a housing havingcompactly arranged terminals for the terminal pitch is reduced. Reducedterminal pitch indicates the spring arms 38 must be shortened, leadingto difficulty for adjustment of the above parameters.

Thus, it is desired to have a terminal configured to overcome the abovementioned deficiencies.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a dual-beam terminal ofa socket connector that allows easy adjustment of contact gap betweenopposite spring arms thereof.

Another object of the present invention is to provide a dual-beamterminal of a socket connector that allows easy adjustment of springrate and thus the normal force acting upon a pin leg engaging therewith.

A further object of the present invention is to provide a dual-beamterminal having a performance adjustable configuration of the beams.

To achieve the above objects, in accordance with the present invention,a socket connector comprises a housing positioned on a circuit board andmovably supporting a cover. Cells are defined in the housing forreceiving and retaining dual-beam terminals. The cover carries a centralprocessing unit module having pin legs extending through holes definedin the cover and partially projecting into the cells of the housing. Thecover is movable in a moving direction to bring the pin legs intoengagement with the corresponding terminals. Each dual-beam terminalcomprises a base section received and firmly retained in thecorresponding cell and a tail extending from the base section and beyondthe housing for being soldered to the circuit board. Two beams extendfrom the base section, substantially opposite to the tail. Each beamforms a spring arm on a free end thereof. The spring arms are oppositeto and spaced from each other for engaging the corresponding pin legtherebetween. The beams are symmetric with respect to an imaginary planethat is normal to the base section and coincident with the movingdirection. Each beam has a major surface angularly offset from theimaginary plane and thus forming a first included angle with theimaginary plane. The major surface also forms a second included anglewith the base section. The included angles are smaller than 90 degreesand greater than 0 degree. Preferably, the included angles are 45degrees. The angularly offset configuration of the beams allows easyadjustment of the space between the spring arms and thus adjustment ofthe performance parameters of the terminals.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be apparent to those skilled in the art byreading the following description of a preferred embodiment thereof,with reference to the attached drawings, in which:

FIG. 1 is an exploded view of a socket connector;

FIG. 2 is a perspective view of a conventional conductive terminal thatcan be received and retained in a cell of the socket connector of FIG.1;

FIG. 3 is a perspective view of a conductive terminal constructed inaccordance with the present invention that can be received and retainedin the cell of the socket connector of FIG. 1;

FIG. 4 is a front view of the conductive terminal of the presentinvention;

FIG. 5 is a side elevational view of the conductive terminal of thepresent invention; and

FIG. 6 is a top view of the conductive terminal of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the drawings and in particular to FIGS. 3-6, aconductive terminal constructed in accordance with the presentinvention, generally designated with reference numeral 100, is to bereceived and retained in a cell 14 defined in a housing 12 of a socketconnector 10 (FIG. 1). The terminal 100 is made by stamping a metalplate and followed by subsequent forming operations. The terminal 100comprises a base section 102 having a first major surface (not labeled).The base section 102 is received in the cell 14 and forms barbed edges104 on opposite sides thereof for interferentially engaging the cell 14to firmly retain the terminal 100 in the cell 14. A tail section 106extends from a lower edge of the base section 102. The tail section 106comprises a solder pad 108 connected to the lower edge of the basesection 102 by a neck portion 109. The neck portion 109 is bent an angleof approximately 90 degrees whereby a second major surface of the solderpad 108 is substantially normal to the first major surface of the basesection 102.

The solder pad 106 can carry a solder ball (not shown) for connectingthe terminal 100 to a circuit board (not shown) by Surface MountTechnology (SMT). However, it is apparent to those having ordinaryskills to form a tail configured to employ the “through-hole” techniquefor connecting the terminal 100 to the circuit board. This is well knownand no further description is necessary herein.

An extension 110 is formed on an upper edge of the base section 102. Twobeams 112 extend from opposite edges of the extension 110 in an upwarddirection that is substantially parallel to the first major surface ofthe base section 102. The beams 112 are spaced from each other foraccommodating movement of a pin leg 22 of an electronic device 20(FIG. 1) in a predetermined moving direction A therebetween. In theembodiment illustrated, the beams 112 are made symmetric with respect toan imaginary central plane P (FIGS. 4 and 6) and the central plane Pbisects the base section 102 and the terminal 100 itself. That is theterminal 100 is symmetric with respect to the central plane P and thusthe moving direction A is coincident with the central plane P. However,it is not necessary to be so.

Each beam 112 has a third major surface angularly offset from the firstmajor surface and the central plane P by a given angle. Namely, thethird major surface forms an included angle B with the first majorsurface of the base section 102 and the third major surface also formsan included angle (not labeled) with respect to the central surface P.The angle B is preferably 45 degrees. In other words, the third majorsurface also forms a 45 degree included angle with respect to thecentral plane P. It is, however, apparent to those having ordinaryskills to adapt a different value of the included angle B. The includedangle B can be any angle greater than 0 degree but smaller than 90degrees.

A spring arm 114 has a proximal section 116 connected to a free end ofeach beam 112 by a connection section 118 and a distal section 120extends from the proximal section 116 and away from the beam 112 in adirection substantially parallel to the moving direction A of the pinleg 22 and the central plane P. The spring arms 114 are symmetrical withrespect to the central plane P.

The proximal sections 116 of the spring arms 114 are spaced from eachother and are arranged to convergent toward each other whereby thedistance between the proximal sections 116 is reduced toward a minimumgap (not labeled) between the distal sections 120. The distal sections120 are substantially parallel to each other and spaced from each otherby the gap that corresponds the minimum distance between the proximalsections 116. The convergent configuration of the proximal sections 116functions to lead the pin leg 22 of the electronic device 20 into thegap between the distal sections 120. The gap between the distal sections120 is selected to have the distal sections 120 of the spring arms 114firmly engage the pin leg 22. The angularly offset beams 112 allowsflexibility in setting and adjusting performance parameters of theterminal 100, such as the gap between the spring arms 114 and the springrate of the beams 112 and the spring arms 114 experienced by the pin leg22.

It is, however, apparent to those skilled in the art to switch thefunctions of the distal sections 120 and the proximal sections 116.Namely, the distal sections 120 are arranged in a convergent manner toserve as a lead-in of the pin leg 22, while the proximal sections 116are substantially parallel to each other as well as the moving directionA of the pin leg 22 (or the central plane P) and form a small gaptherebetween for electrically and mechanically engaging the pin leg 22.

In the embodiment illustrated, the connection section 118 are inclinedtoward the central plane P and thus convergent toward each other as theyextend away from the beams 112 for reducing the distance between thespring arms 114 and also for more flexibility in setting and adjustingthe performance parameters.

Although the present invention has been described with reference to thepreferred embodiment thereof, it is apparent to those skilled in the artthat a variety of modifications and changes may be made withoutdeparting from the scope of the present invention which is intended tobe defined by the appended claims.

What is claimed is:
 1. A conductive terminal comprising: a base sectionadapted to be received and firmly retained in a cell defined in ahousing, the base section having a first major surface; two beamsextending from a first edge of the base section and symmetric withrespect to an imaginary plane, each beam having a major surfaceangularly offset with respect to the imaginary plane by an angle; and atail extending from a second edge of the base section and opposite tothe beams; wherein each beam forms a spring arm, the spring arms beingsymmetrical with respect to the imaginary plane, each spring armcomprising a lead-in section and an engaging section, the lead-insections being convergent toward the imaginary plane with a distancebetween the lead-in sections gradually reduced to a minimum gap betweenthe engaging sections; wherein each spring arm is connected to thecorresponding beam by an inclined connection section; wherein theinclined connection section connects the engaging section of each springarm to a free end of the corresponding beam; wherein the tail comprisesa solder pad connected to the second edge of the base section by a neckportion whereby the solder pad is substantially normal to the firstmajor surface of the base section; wherein the base section forms barbedside edges for interferentially engaging the cell.
 2. The conductiveterminal as claimed in claim 1, wherein the offset angle is around 45degrees.
 3. A socket connector adapted to mount an electronic devicehaving pin legs to a circuit board, the socket connector comprising: ahousing defining cells therein; a cover movably supported on the housingand defining through holes corresponding to the cells, the cover beingadapted to carry the electronic device with the pin legs extendingthrough the holes of the cover and partially extending into the cells ofthe housing and move the electronic device and the pin legs in a givenmoving direction with respect to the housing; and a conductive terminalcomprising: a base section received and fixed in each cell of thehousing; two beams extending from a first edge of the base sectiontoward the cover, each beam forming a spring arm, the spring arms beinglocated on opposite sides of an imaginary plane parallel to the movingdirection, and spaced from each other for accommodating the movement ofthe pin leg therebetween, each spring arm comprising a lead-in sectionand an engaging section, the lead-in sections being convergent towardthe imaginary plane with a distance between the lead-in sectionsgradually reduced to a minimum gap between the engaging sections wherethe pin leg engages the spring arms; and a tail extending from a secondedge of the base section and opposite to the beams, the tail beingadapted to be soldered to the circuit board; wherein each beam has amajor surface angularly offset with respect to the imaginary plane by anangle; wherein each spring arm is connected to the corresponding beam byan inclined connection section; wherein the inclined connection sectionconnects the engaging section of each spring arm to a free end of thecorresponding beam; wherein the tail comprises a solder pad connected tothe second edge of the base section by a neck portion whereby the solderpad is substantially normal to the base section; wherein the offsetangle is smaller than 90 degrees and greater than 0 degree; wherein thespring arms are symmetric with respect to the imaginary plane; whereinthe base section has a major surface substantially normal to theimaginary plane and wherein the imaginary plane bisects the base sectionwhereby the terminal is substantially symmetric with respect to theimaginary plane.
 4. The socket connector as claimed in claim 3, whereinthe base section forms barbed side edges for interferentially engagingthe cell of the housing.
 5. The socket connector as claimed in claim 3,wherein the offset angle is around 45 degrees.